Nine suspected cartel gunmen were killed in two clashes with army soldiers on the outskirts of this northern Mexican industrial city, officials said.

Four of the men were killed Thursday in a gun battle in a wooded area on the northeastern outskirts of Monterrey after around 50 special forces soldiers from the 7th Military Zone spotted them traveling in two SUVs, a state security spokesman said.

An army officer who participated in the operation said the remote area was being used by an organized crime gang as a firearms training grounds for young recruits.

The other clash between suspected organized crime members and army soldiers took place Thursday morning on the streets of Cadereyta, a town 35 kilometers (21 miles) outside Monterrey, after the military personnel tried to stop an SUV carrying the gunmen.

Soldiers from the 7th Military Zone pursued the vehicle after coming under fire from the assailants.

Five gunmen were killed in the clash and soldiers also confiscated seven assault rifles at the scene.

Monterrey, Mexico's most important industrial city, and its suburbs have been battered by a wave of drug-related violence since March 2010, when three rival cartels reportedly went to war with Los Zetas.

Los Zetas has been battling an alliance of the Gulf, Sinaloa and La Familia drug cartels, known as the Nueva Federacion, for control of the Monterrey metropolitan area and smuggling routes into the United States.

Heriberto Lazcano Lazcano, known as "El Lazca," deserted from the Mexican army in 1999 and formed Los Zetas with three other soldiers, all members of an elite special operations unit, becoming the armed wing of the Gulf drug cartel.

After several years on the payroll of the Gulf cartel, Los Zetas, considered Mexico's most violent criminal organization, went into the drug business on their own account and now control several lucrative territories.

A total of 267 murders were registered in the industrial city in 2009, with the figure rising to 828 in 2010 and more than 700 so far this year, and 80 percent of the killings are related to drug trafficking, official figures show.